Fuel pump and method of control therefor

ABSTRACT

An engine fuel pump of the type having a pulsating diaphragm operated in one direction by an engine driven member, such as an oscillating arm driven by an eccentric on the engine cam shaft, and operated in the other direction by a spring which establishes output or pumping pressure to the needle valve of a float-type carburetor, the pump having inlet and outlet valves which operate upon demand of fuel to the carburetor and permits the diaphragm to pulsate accordingly, characterized by a by-pass valve controlled by intake manifold pressure which by-passes a metered flow of fuel from a pumping chamber to the inlet side of the inlet valve to thereby reduce pumping pressure at normal automotive speeds at which pumping pressure is in excess of that required and which results in an abnormally high fuel level in the carburetor, causing excessive consumption of fuel or flooding of the carburetor, the by-pass becoming inoperative at higher than normal speeds to permit the pumping pressure to increase to its normal designed value at such higher speeds and at which the pumping pressure will not cause the malfunctions referred to which occur at the normal automotive speeds.

United States Patent 1 Bandimere 1 1 June 12, 1973 1 FUEL PUMP AND METHOD OF CONTROL THEREFOR [76] Inventor: John C. Bandimere, 3740 Fenton St.,

Wheatridge, Colo. 80033 [22] Filed: Sept. 5, 1969 [21] Appl. No.: 855,652

[52] U.S. Cl. 123/139 AF, 123/140 MP [51] Int. Cl. F02!!! 69/00 [58] Field of Search 123/139 A, 139.6,

[56] References Cited UNITED STATES PATENTS 1,881,860 10/1932 Muzzy 123/1396 2,942,550 6/1960 Carter 417/307 2,964,029 12/1960 Tirloni 123/139 Primary ExaminerCarlton R. Croyle Assistant ExaminerWarren Olsen tt0meySheridan, Ross & Burton and Victor C. Muller [57] ABSTRACT An engine fuel pump of the type having a pulsating diaphragm operated in one direction by an engine driven member, such as an oscillating arm driven by an eccentric on the engine cam shaft, and operated in the other direction by a spring which establishes output or pumping pressure to the needle valve of a float-type carburetor, the pump having inlet and outlet valves which operate upon demand of fuel to the carburetor and permits the diaphragm to pulsate accordingly, characterized by a by-pass valve controlled by intake manifold pressure which by-passes a metered flow of fuel from a pumping chamber to the inlet side of the inlet valve to thereby reduce pumping pressure at normal automotive speeds at which pumping pressure is in excess of that required and which results in an abnormally high fuel level in the carburetor, causing excessive consumption of fuel or flooding of the carburetor, the bypass becoming inoperative at higher than normal speeds to permit the pumping pressure to increase to its normal designed value at such higher speeds and at which the pumping pressure will not cause the malfunctions referred to which occur at the normal automotive speeds.

1 Claim, 3 Drawing Figures PATENTEB M i 2 $35 INVENTOR JOHN C. BAND/MERE BY M l a/ M ATTORNEYS FUEL PUMP AND METHOD OF CONTROL THEREFOR BACKGROUND OF THE INVENTION Automotive vehicles have long been provided with engine driven fuel pumps which deliver fuel from the fuel tank to a carburetor, the level in the bowl of which is controlled by a needle valve operated by a movable float. The AC company has long furnished such pumps to automobile manufacturers and many copies of same have been manufactured by others. Briefly, such type of pump employs a pulsating diaphragm as heretofore referred to, which is urged by a return spring on its pumping stroke and is operated in its opposite direction by power from the engine. A pump of the type referred to, together with its more detailed mode of operation, is disclosed in Auto Mechanics, 1963, published by Goodheart-Willcox Co., I-Iomewood, Ill., pages 6-5 through 6-l l and in Audels Compact Auto Repair Manual, I963, Indianapolis, Ind., pages 32-34. The design has been found to provide adequate fuel flow under certain automobile operating speeds where high fuel consumption is required, such as at full or near full throttle conditions; however, at lower speeds, such as idle or normal cruising speeds such pump may provide excessive pressure which may result in an abnormally high fuel level in the carburetor'bowl or even overflowing or flooding of same, both of which are obviously undesirable. It might appear obvious that by suitable choice of the diaphragm spring the pumping pressure could be reduced if desired but it would then be inadequate for the conditions of high automotive speed and fuel consumption. It thus becomes apparent that the solution to this problem does not reside in alteration of the pumping spring. Pressure regulators have been proposed which control the fuel supply pressure but these have not entirely solved the problem since it is characteristic of such regulators to maintain a constant pressure irrespective of the rate of fuel flow and at high rates of consumption they would supply less fuel than required. It is now believed apparent that the regulation of pressure should be such that under certain operating conditions it is lower than the designed pressure but at other operating conditions it returns to normal designed pressure.

SUMMARY OF THE INVENTION The present invention provides a solution to the problem referred to by the provision of a by-pass valve which permits a controlled by-pass from the pumping chamber, or a delivery conduit connected to same, to the inlet side of the pump inlet valve, thereby reducing pumping pressure. This condition is maintained throughout the normal operating speeds or engine loads to reduce the designed pumping pressure to a value which will be optimum for carburetor operation, but at speeds or loads above normal, the pumping pressure is permitted to resume its normal designed .pressure. It is thus in the nature of a pressure regulator but is to be distinguished from conventional regulators which constantly maintain a desired pressure, regardless of rate of flow, in that it regulates pressure throughout one range of conditions to an optimum value but during another range of conditions it permits a pressure to resume its designed value, which designed value was not optimum for both conditions.

It is thus a general object of this invention to provide method and improved apparatus for attaining the results just referred to.

Another object is to provide the improved apparatus in a fuel pump as originally manufactured.

Another object is to provide the improved apparatus as a retrofit or modification to a pre-existing fuel pump.

A further object is to provide the improved apparatus as an accessory for use with a pre-existing fuel pump and without modifications to the internal parts of the pre-existing fuel pump.

Still further objects, advantages, and salient features will become more apparent from the description to fol low, the appended claims, and the accompanying drawing to now be briefly described.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a central section through a conventional fuel pump, illustrated in simplified form, with an exemplary form of the invention incorporated in same;

FIG. 2 is an enlarged detail of FIG. 1; and

FIG. 3 diagrammatically illustrates another form of the invention.

DESCRIPTION OF PREFERRED EMBODIMENTS Referring now to the drawing, and first to FIG. 1, fuel pump 10 is illustrated in somewhat simplified form and may be considered to be of the general type illustrated in the books referred to, comprising a pump body 12 containing a pumping diaphragm l4, operated in one direction by a pull rod 16 and in the opposite direction by a spring 18, the diaphragm forming one wall of a pumping chamber 20 which communicates with inlet pipe 22, via an inlet check valve 24, and with outlet pipe 26, via an outlet check valve 28. As will be understood, when pull rod 16 is operated by the conventional rocker arm (not shown) in the direction of the arrow on the pull rod, fuel flows into chamber 20 and spring 18 is compressed. Inlet valve 24 then closes and spring 18 delivers the fuel through outlet valve 28 as the carburetor demands same, this demand being controlled by a float actuated needle valve in the carburetor (not shown). As will be apparent, the unit pumping pressure is established by the force of the spring acting upon the area of the pumping diaphragm. The pump is further conventional in that it is provided with a pulsator diaphragm 30, secured to the pump body by a cover 31 and providing chambers 32, 34 in which air is trapped, the compression and expansion of which acts as a spring to smoothen the pulsating flow through the pump.

The modifications to the conventional pump, so far described, comprise a by-pass tube 36 affixed to a partition 38 in a pulsator 39 which separates inlet and outlet chambers 40, 42. A metered or jet passage 44, shown in detail in FIG. 2, is provided in the tube and the surface of the pulsator diaphragm forms a valve for closing the flat annular end 46 of the tube surrounding the metering orifice. The annular end is preferably provided with a small radial nick or groove 48 to provide a leakage path to the metering orifice when it is closed by the pulsator diaphragm. A spring 50 urges the pulsator diaphragm into seating engagement with the end of the by-pass tube and a conduit 52 communicates chamber 34 with the carburetor intake manifold, the partial vacuum in which is sufficient to unseat the pulsator diaphragm against the urge of spring 50 which seats it under certain engine operating conditions.

In the operation of the pump it will first be assumed that a vehicle is in operation at partial throttle, that is, at a speed or load which maintains a relatively high vacuum in the intake manifold. Under this condition, manifold pressure unseats the pulsator diaphragm and a portion of the fuel in outlet chamber 42 is constantly by-passed back to inlet chamber 40, thus reducing the pressure in chamber 42 and to the carburetor needle valve, permitting the carburetor needle valve to maintain a lower float level than would have been possible in the absence of the by-pass and with formerly higher pressure. Let it now be assumed that the engine is operated at an increased throttle opening for increased vehicle speed or load. The vacuum in the manifold now decays to a new value (increase in absolute pressure) and spring 50 now closes the by-pass, permitting the pressure in chamber 42 to resume the normally designed pressure in same. 1

As so far described, the invention is employed with an exemplary type of fuel pump which incorporates a pulsator diaphragm. In pre-existing pumps the only modifications required are to install tube 36 which may be readily attained by drilling a suitable hole through partition 38; adding spring 50; and providing a fitting 52 for communication with the intake manifold. In view of the simplicity of this retrofit it will also be apparent that it may be readily incorporated in the pump at the time of manufacture, both of which constructions are thus contemplated.

Some pumps, however, are not provided with a pulsator diaphragm as so far described, and their conversion by internal modifications could present problems which are not subject to such economical conversion or modification. It is thus also contemplated that in such cases the invention may be practiced without disturbing or modifying the internal parts of such pumps by the provision of an accessory which may be associated with a pump and connected to it with conventional pipe or tubing fittings.

FIG. 3 diagrammatically illustrates an accessory for a fuel pump of the type just referred to. Pump a is of any well known type having an inlet valve 24a and outlet valve 28a. It will again be understood that the designed outlet or delivery pressure is higher than required at certain normal conditions of operation but is of proper design to supply the engine requirements at conditions, such as at full or near full carburetor throttle conditions. The accessory 39a has similarities to pulsator 39 in that it includes inlet and outlet chambers 40a, 42a, a diaphragm 30a, a by-pass 36a which may be closed by the diaphragm under urge of a spring 50a,

and a connection 52a which communicates with the intake manifold. Suitable tubes 54, 56 communicate accessory 39a with the conventional inlet and outlet pipes 22a, 26a of pump 100. As will be apparent, outlet or delivery pressure in outlet 26a is reduced through the by-pass to inlet 22a in the same manner as in FIG. 1.

The purpose of nick or groove 48, previously referred to, which may be employed in the modification of FIG. 3, as well as in FIG. 1, is to permit the pressure in chamber 42 (or 42a) to decay to ambient pressure when operation of the engine is discontinued to thus prevent further flow through the carburetor needle valve which might raise the carburetor fuel level and cause flooding.

It is to be understood that this invention is not limited to the exact embodiments of the device shown and described, which are merely by way of illustration.

I claim:

1. In an engine driven fuel pump of the type having an oscillating diaphragm adapted to pump only by the urge of a spring and having inlet and outlet valves associated with a pumping chamber, the pump adapted to deliver fuel to a carburetor having a bowl, the fuel level in which is maintained by a float and bowl inlet valve operated by same, the improvements in combination, comprising:

a. means for reducing a predetermined pumping pressure at engine speeds or loads corresponding to a normal range of operation of the engine and at which the entire predetermined pressure is not required,

and for resuming the predetermined pumping pressure at engine speeds or loads corresponding to a greater than normal range of operation and at which the entire predetermined pressure is required,

b. said means comprising a metered bleed conduit positioned between said pumping chamber and the inlet side of said inlet valve, a spring-biased diaphragm cooperating with said bleed conduit for bleeding flow therethrough during normal engine operation and for substantially closing said conduit in response to an engine operating condition which senses a greater than normal range of operation; and

c. a leakage path in said metered bleed conduit for permitting pumping pressure to decay to ambient pressure when operation of the engine is discontinued, whereby pressure on the bowl inlet valve also decays and obviates further supply of fuel to the carburetor bowl during discontinued operation of the engine. 

1. In an engine driven fuel pump of the type having an oscillating diaphragm adapted to pump only by the urge of a spring and having inlet and outlet valves associated with a pumping chamber, the pump adapted to deliver fuel to a carburetor having a bowl, the fuel level in which is maintained by a float and bowl inlet valve operated by same, the improvements in combination, comprising: a. means for reducing a predetermined pumping pressure at engine speeds or loads corresponding to a normal range of operation of the engine and at which the entire predetermined pressure is not required, and for resuming the predetermined pumping pressure at engine speeds or loads corresponding to a greater than normal range of operation and at which the entire predetermined pressure is required, b. said means comprising a metered bleed conduit positioned between said pumping chamber and the inlet side of said inlet valve, a spring-biased diaphragm cooperating with said bleed conduit for bleeding flow therethrough during normal engine operation and for substantially closing said conduit in response to an engine operating condition which senses a greater than normal range of operation; and c. a leakage path in said metered bleed conduit for permitting pumping pressure to decay to ambient pressure when operation of the engine is discontinued, whereby pressure on the bowl inlet valve also decays and obviates further supply of fuel to the carburetor bowl during discontinued operation of the engine. 